Chicken Pecking???

So yesterday evening I go to feed/water and I find one of my 5 week old RIRs has a patch of missing feathers and what looks like a small sore/scratch in the lower mid area of its back. The first thing I think is that the other 5 week old chicks ( RIR, Delawares & Blue Andalusians ) are pecking it. I spend a good deal of time taking care of my chicks and have never observed this behaviour and have no reason to believe that that is what is happening, but it's what I suspect. Could be that it somehow scratched itself on the wire of the borrowed temporary pen, or something tried to get at it from outside the pen ( we live close to woods and do have possums and coons come into the yard at night ), but just not sure. Anyway ... I brought it in and my wife cleaned the area and we put some antibiotic cream on it to hopefully keep it from getting infected. Is this ok? Do I need to treat it differently? And if it turns out to be pecking is there anything I can do about that?

That's awfully young for a pecked mark like that....I've seen it with my adult chickens occasionally, but not with the young'uns. It sure sounds like, as you've described it, a very common place for pecking to happen. You know, why not sit a spell, and just watch them for a while. You will see if one of them is a pecker.

On the other hand, your chick could have gotten stuck under some chicken wire, or scratched somehow, that's true. A predator like a raccoon, with those little paws that are similar to hands could try and reach in and grab one......

If you can put the chick back with the others, just kind of watch to see if they're attracted to the wound, because chickens see something abnormal, (especially if it's red, like blood), and they will peck at the spot.

Do you think they've got enough room? If they're a bit crowded, that can cause pecking. If they do have plenty of room, maybe you can add something in there to make things interesting like a branch for roosting, or something they might like to peck at.....

You might want to put something like Blu-Kote on it, it is a purple colored antiseptic spray that colors the wound and helps keep the other birds from pecking on it again. You can get it at most farm stores in the livestock section.
X2, check how much space the chicks have, overcrowding if a common cause for feather plucking. Also try giving them things to do in the pen, ie put some hay in there for them to scratch around in, a little scratch, branches etc to jump on.